The Gullfaks giant oil field in the Norwegian sector of the North Sea was discovered in 1978. The Gullfaks field contains oil reserves on the order of 230 million standard m³.

Gullfaks represents the shallowest structural element of the Tampen spur. It was formed during the Upper Jurassic to Lower Cretaceous as a sloping high, with a westward structural dip gradually decreasing toward the east. The major north-south-striking faults, with eastward-sloping fault planes, divide the field into several rotated fault blocks. The central and eastern parts of the structure were eroded by the Early Cretaceous transgression.

The reservoir sands are the Middle Jurassic delta-deposited Brent Group, the Lower Jurassic shallow marine sandstones of the Cook Formation, and the Lower Jurassic fluvial channel and delta plain deposits of the Statfjord Formation.

The Brent reserves in the western part of the field are currently being developed from the Gullfaks A and B platforms, and the eastern part is being developed from a third platform, Gullfaks C. Water injection is the major drive mechanism, maintaining the reservoir pressure above the bubble point.

One of the most important factors in the reservoir development of the Gullfaks field has been the effect of fault transmissibilities on lateral and vertical pressure distributions.

End_Page 429------------------------